1. Field of the Invention
This invention relates to a medical device, and in particular to a delivery device for an endoluminal prosthesis.
2. Description of Related Art
The deployment of endoluminal prostheses into the lumen of a patient from a remote location by the use of a deployment device is generally known. An endoluminal prosthesis may be retained in a radially constrained state within a sleeve until it is deployed. To deploy the prosthesis, the sleeve is withdrawn from the prosthesis allowing the prosthesis to expand. The prosthesis may be radially self-expanding or it may be balloon expandable. The prosthesis may comprise a graft and/or a stent.
U.S. Published Patent Application Nos. 20040098079, 20040106974, 20050085890, and 20050060018, which are herein incorporated by reference, disclose various delivery devices for an expandable endoluminal prosthesis. The expandable endovascular prosthesis comprises a bare self-expanding stent disposed on an end portion thereof. The self-expanding stent may comprise a plurality of barbs that in use are adapted to anchor the prosthesis to a surrounding body lumen. A cover retains an end portion of the self-expanding stent on the delivery device in a radially constrained state. To deploy the prosthesis, the operator withdraws the cover from the self-expanding stent, thereby exposing the stent and allowing it to expand radially outwardly.
The stent radially expands against an inner surface of the cover prior to deployment. The expansion force of the stent against the inner surface can be sufficiently high so as to create significant interference between the stent and the cover. This can result in increased operating effort to remove the cover from the stent. This is particularly true where the stent comprises sharpened barbs that may scratch or dig into the inner surface of the cover.